refactor:캐시미스시 db 조회 부분 공통 로직으로 분리

Author: yeonjiyeon

apps/commerce-api/src/main/java/com/loopers/support/cache/RedisCacheHandler.java

@@ -0,0 +1,52 @@
+package com.loopers.support.cache;
+
+import com.loopers.support.page.PageWrapper;
+import java.time.Duration;
+import java.util.function.Supplier;
+import lombok.RequiredArgsConstructor;
+import org.springframework.data.domain.Page;
+import org.springframework.data.redis.core.RedisTemplate;
+import org.springframework.stereotype.Component;
+
+@RequiredArgsConstructor
+@Component
+public class RedisCacheHandler {
+  private final RedisTemplate<String, Object> redisTemplate;
+
+  /**
+   * 캐시 조회 -> (없거나 에러나면) -> DB 조회 -> 캐시 저장
+   * @param key        캐시 키
+   * @param ttl        만료 시간
+   * @param type       반환 타입 (캐스팅용)
+   * @param dbFetcher  DB 조회 로직 (람다)
+   */
+  public <T> T getOrLoad(String key, Duration ttl, Class<T> type, Supplier<T> dbFetcher) {
+    try {
+      Object cachedData = redisTemplate.opsForValue().get(key);
+      if (cachedData != null) {
+
+        if (cachedData instanceof PageWrapper) {
+          return (T) ((PageWrapper<?>) cachedData).toPage();
+        }
+        return type.cast(cachedData);
+      }
+    } catch (Exception e) {
+    }
+
+    T result = dbFetcher.get();
+
+    if (result != null) {
+      try {
+        Object dataToSave = result;
+        if (result instanceof Page) {
+          dataToSave = new PageWrapper<>((Page<?>) result);
+        }
+
+        redisTemplate.opsForValue().set(key, dataToSave, ttl);
+      } catch (Exception e) {
+      }
+    }
+
+    return result;
+  }
+}